1. Field of the Invention
The invention relates to the field of methodology and devices in which desired materials are selectively withdrawn from a mixed accumulation of materials and segregated as a concentrated accretion of said selectedly withdrawn material.
In particular, the invention relates to means and method whereby a dry mixture of ore fines and tailings are fluidized and the fines withdrawn from the fluidized mix to yield a concentrated accumulation of fines.
2. Prior Art
The prior art known to the inventor neither anticipates nor makes obvious the present invention. As an example of the prior art known in the field of segregating materials by variations in the weight (mass) of the materials, the inventor herein cites the U.S. patents of Hinds et al, issued Aug. 25, 1942 as U.S. Pat. No 2,294,086; and of Isogaya, issued July 21, 1981 as U.S. Pat No 4,279,740. Both use air to separate materials by their differing masses; while Isogaya also employs electrostatic attraction to draw light weight materials to a collection drum.
The Hinds et al patent issued for a PNEUMATIC SEPARATING APPARATUS. The materials to be separated were two distinctly different materials one of which was relatively light with respect to the other. The materials to be separated were deposited on a continuous (sometimes referred to as "endless") belt. The upper surface of this first continuous belt passed a distance beneath and parallel to the under surface of a second continuous belt. Both surfaces preferably travel in the same direction and are of an open mesh to allow the passage of air therethrough. When air is passed through the two belts and the mass of materials, the lighter (less massive) of the two materials is transported upward and deposited against the lower surface of the second continuous belt. The heavier, or more massive, material remains on the upper surface of the lower continuous belt. The two materials are thus effectively segregated and means for their separate collection are readily conceived.
The Isogaya patent issued for a LIGHT-MATERIAL SEGRAGATING METHOD AND APPARATUS. Isogaya is faced with the same problem as Hinds et al: separating relatively very light material from a heavy material. As with Hinds et al, the materials to be separated are deposited onto the upper surface of a continuous belt through which a stream of air is passed. However, instead of employing a second continuous belt, Isogaya uses an array of rollers above the material. Each roller is slightly spaced apart from its adjacent roller so the air passing through the material on the continuous belt will move upward and through the spaces between rollers, hopefully transporting light-weight material through those spaces as well.
To enhance the transporting effect of the moving air, Isogaya creates a vacuum above the array of rollers. As a further enhancement to the separation of materials from the mass, the rollers are electrostatically charged. Materials, such as powdered substances and hair, are readily attracted to the charged surfaces of the rollers. To prevent these substances from accumulating on the roller surfaces, the rollers are caused to rotate whereby the adhering material is drawn into the air stream moving through the spaces between the rollers and drawn from the roller surface toward the vacuum source.
Neither Hinds et al nor Isogaya attempt to percolate air through the mass of materials to be separated such that the mass becomes fluidized and particles of various weights migrate to their own segregated strata within the fluid mass. Neither of them teach that the particles of the fluidized mass may be further segregated by electrostatically inducing a charge on the particles themselves. Neither teach that the mass may be fluidized between oppositely traveling surfaces of adjacent moving belts, which opposed travel aids in accumulating selected, segregated material from the fluid mass. Nor do Hinds et al and Isogaya teach that variations in the speed of travel of the oppositely moving belts may be utilized to enhance the selective accumulation of materials from the fluid mass. These latter features are taught here by the instant inventor.